Part of it is that Bill Clinton is crazy like a fox.
The more his face turns purple from seeming anger, and the more he rails against Barack Obama with half-truths and total distortions, the better his wife seems to fare in her race for the Democratic presidential nomination. That's regardless of the South Carolina outcome, which was a probably aberrant case.
Generally speaking, Bill and Hillary have managed to take this supposedly transcendent and transformational political figure -- so evident in Obama's soaring victory address after the Iowa caucuses -- and turn him into a rabid babbler worthy of the McLaughlin Group.
They brought Obama down several notches, from inspiration to -- in that debate the other night -- just another bickering politician as usual.
They picked at him until he snapped.
Another part of it is that Bill surely owes his wife. The fidelity he didn't deliver as a husband can now be redeemed by his willingness to surrender his global statesmanship in service to her as her hatchet man.
But I wonder if there isn't another factor, more personal to Bill. I'm thinking that he, independent of Hillary's needs, sees Barack as a rival and threat, and is jealous.
If Barack becomes president, we will have our first real black president. Toni Morrison's characterization of Clinton will be moot, overpowered.
And what is Obama's political essence? It is two-pronged -- generational change and racial eloquence. And those only happen to have been Bill's things.
Clinton was the one who said "change" in rat-a-tat fashion as a candidate for president in 1992. He was the one who would dare to go to a black audience and attack a black rapper's lyrics, and not only get away with it with blacks, but send a message to white people in the process. He was the one who would go to Memphis and give a sermon about how Martin Luther King Jr. didn't live and die so that young black men could do drugs and kill each other on the streets.
Now comes Obama, 15 years Clinton's junior, proposing to render Clinton a blip on the screen in broad historical terms.
This hit me most powerfully when I beheld Obama's sermon last Sunday in King's church in Atlanta.
It is important to make the point that a speech is but a speech, and that the ability to deliver a good one does not in itself connote greatness. Mike Huckabee can give a good speech.
Obama's sermon was about how the walls of Jericho came tumbling down after God explained to Joshua and the Israelites that they could only scale the city's steps through unity. From this parable Obama talked of King's plea for unity and the power therein.
He said we must stress our commonality rather than obsess on our differences -- a recurring theme in Clinton's recent ex-presidential oratory.
Then Obama said that black people need to remember that, while they've been on the losing end of oppression, they haven't always been exactly brotherly and sisterly toward gays and Jews, or each other.
Albeit without any of those nagging specifics, Obama wove all this into his theme of a new day, a new hope, a new togetherness, a new politics.
It's the same kind of expansive and inclusive theme by which Obama could cite the plain facts -- wholly distorted by the Clintons -- that Republicans have had more ideas than Democrats in recent decades, and that Reagan, not Clinton, was a transformational political figure.
All of that is to suspect this: While Bill takes on Obama in behalf of his wife, he also wages his own personal battle with the talented young upstart.
John Brummett is an award-winning columnist for the Arkansas News Bureau in Little Rock and author of "High Wire," a book about Bill Clinton's first year as president. His e-mail address is jbrummett@ arkansasnews.com.